Lister-V (dietary supplement no.14)

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Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

Cyp1a2 Inhibitors/Fezolinetant

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Inhibitors of CYP1A2 may inhibit the metabolism of fezolinetant.(1-4)

CLINICAL EFFECTS: Concurrent use of a CYP1A2 inhibitor may increase levels of and adverse effects from fezolinetant.(1-4)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Recommendations for concurrent use of fezolinetant with CYP1A2 inhibitors differ in different regions. The US manufacturer of fezolinetant states that concurrent use with strong, moderate, and weak CYP1A2 inhibitors is contraindicated.(1) The Australian, Canadian, and UK manufacturers of fezolinetant state that concurrent use with strong and moderate CYP1A2 inhibitors is contraindicated, while weak CYP1A2 inhibitors are not predicted to cause clinically relevant changes in fezolinetant exposure.(2-4)

DISCUSSION: In a study, fluvoxamine, a strong CYP1A2 inhibitor, increased fezolinetant maximum concentration (Cmax) and area-under-curve (AUC) by 80% and 840%, respectively. Mexiletine (400 mg every 8 hours), a moderate CYP1A2 inhibitor, increased fezolinetant Cmax and AUC by 40% and 360%, respectively. Cimetidine (300 mg every 6 hours), a weak CYP1A2 inhibitor, increased fezolinetant Cmax and AUC by 30% and 100%, respectively.(1) Strong CYP1A2 inhibitors linked to this monograph include angelica root, ciprofloxacin, enasidenib, enoxacin, fluvoxamine, and rofecoxib. Moderate CYP1A2 inhibitors linked to this monograph include capmatinib, centanafadine, dipyrone, fexinidazole, genistein, hormonal contraceptives, methoxsalen, mexiletine, osilodrostat, phenylpropanolamine, pipemidic acid, rucaparib, troleandomycin, vemurafenib, and viloxazine. Weak CYP1A2 inhibitors linked to this monograph include acyclovir, allopurinol, artemisinin, belumosudil, caffeine, cannabidiol, cimetidine, curcumin, dan-shen, deferasirox, disulfiram, Echinacea, famotidine, ginseng, norfloxacin, obeticholic acid, parsley, piperine, propafenone, propranolol, ribociclib, simeprevir, thiabendazole, ticlopidine, triclabendazole, valacyclovir, verapamil, and zileuton.(5-7)

Cyp3a4 Inducers/Lumateperone

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Lumateperone is a substrate of CYP3A4. Inducers of CYP3A4 may induce the metabolism of lumateperone.(1)

CLINICAL EFFECTS: The concurrent administration of a CYP3A4 inducer may decrease the exposure to lumateperone.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of lumateperone states that concurrent use with CYP3A4 inducers should be avoided.(1)

DISCUSSION: Coadministration of lumateperone with rifampin, a strong CYP3A4 inducer, resulted in a 98% reduction in area-under-curve (AUC) and a 90% reduction in concentration maximum (Cmax).(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2,3) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, repotrectinib, rifabutin, telotristat, thioridazine, and tovorafenib.(2,3) Weak inducers of CYP3A4 include: amprenavir, armodafinil, aumolertinib, bexarotene, brivaracetam, clobazam, danshen, darolutamide, dexamethasone, dicloxacillin, echinacea, eslicarbazepine, garlic, genistein, gingko, ginseng, glycyrrhizin, nevirapine, omaveloxolone, oxcarbazepine, pioglitazone, quercetin, rufinamide, sotorasib, sulfinpyrazone, sunvozertinib, tecovirimat, terbinafine, ticlopidine, troglitazone, vemurafenib, and vinblastine.(2,3)

Cyp3a4 Inducers/Zuranolone

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Inducers of CYP3A4 may induce the metabolism of zuranolone.(1)

CLINICAL EFFECTS: Concurrent use of a CYP3A4 inducer may result in a loss of zuranolone efficacy.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of zuranolone with CYP3A4 inducers.(1)

DISCUSSION: Coadministration of zuranolone with rifampin decreased the maximum concentration (Cmax) by 0.31-fold and area-under-curve (AUC) by 0.15-fold.(1) Strong CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort. Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib. Weak CYP3A4 inducers linked to this monograph include: armodafinil, aumolertinib, bexarotene, brigatinib, brivaracetam, clobazam, danshen, darolutamide, dexamethasone, dicloxacillin, echinacea, eslicarbazepine, flucloxacillin, garlic, genistein, ginseng, glycyrrhizin, methylprednisolone, mobocertinib, nevirapine, omaveloxolone, oritavancin, oxcarbazepine, pioglitazone, pitolisant, quercetin, relugolix, rufinamide, sarilumab, sulfinpyrazone, sunvozertinib, tazemetostat, tecovirimat, terbinafine, ticlopidine, topiramate, troglitazone, vemurafenib, vinblastine, and zanubrutinib.(2,3)

P-Glycoprotein (P-GP) Inducers/Vincristine

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Inducers of P-glycoprotein (P-gp) may reduce systemic exposure to vincristine.(1)

CLINICAL EFFECTS: Concurrent or recent use of P-gp inducers may result in decreased effectiveness of vincristine.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of vincristine states that concurrent use of P-gp inducers should be avoided.(1) Consider the use of agents with no or minimal induction potential if possible. Monitor patients for decreased response to therapy.

DISCUSSION: Vincristine is transported by P-gp and inducers of this transporter are expected to decrease levels of vincristine.(1) Inducers of P-gp include linked to this monograph include: efavirenz, green tea, and lorlatinib.(2,3)

P-Glycoprotein (P-GP) Inducers; Phenobarbital/Ravidasvir

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Inducers of P-glycoprotein (P-gp) may decrease the absorption of ravidasvir.(1)

CLINICAL EFFECTS: Concurrent or recent use of a P-gp inducer may result in decreased levels and effectiveness of ravidasvir.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of ravidasvir states concurrent use with P-gp inducers is contraindicated.(1)

DISCUSSION: Interaction studies with P-gp inducers have not been performed. Co-administration with potent inducers of P-gp are expected to decrease ravidasvir plasma concentrations and result in therapeutic failure.(1) Agents linked to this monograph include apalutamide, carbamazepine, fosphenytoin, green tea, lorlatinib, phenobarbital, phenytoin, primidone, quercetin, rifabutin, rifampin, and St. John's wort.(1-3)

Xanthine Derivatives/Adenosine; Hexobendine; Regadenoson

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Xanthine derivatives may antagonize the effects of endogenous(1) and exogenous adenosine,(2,3) regadenoson,(4) and hexobendine.(5)

CLINICAL EFFECTS: Concurrent use of a xanthine derivative use may result in decreased effectiveness of adenosine, hexobendine and regadenoson. Aminophylline may increase the risk of adenosine-induced seizures.(3)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients receiving concurrent therapy with adenosine and a xanthine derivative should be monitored for decreased effectiveness of adenosine. The dosage of adenosine may need to be increased. Whenever possible, withhold xanthine derivatives for 5 half-lives prior to using adenosine in cardiac stress tests.(6) Methylxanthines should not be used to reverse the effects of adenosine in patients who experience adenosine-induced seizures.(3) Concurrent therapy with hexobendine and a xanthine oxidase derivative should also be monitored for decreased effectiveness of hexobendine.(5) The US manufacturer of regadenoson recommends that patients avoid methylxanthines (e.g. caffeine, pentoxifylline, and theophylline) for 12 hours prior to regadenoson administration. Aminophylline may be used to attenuate severe and/or persistent adverse reactions to regadenoson.(4)

DISCUSSION: In a study in six healthy subjects, theophylline significantly reduced the heart-rate response to adenosine. In addition, theophylline reduced the amount of abdominal and chest discomfort reported by subjects, allowing significantly higher infusion rates of adenosine.(7) Theophylline has also been reported to antagonize the vasorelaxant action of adenosine in human forearm arterioles.(8) In a study in five subjects, theophylline decreased the amounts of adenosine-induced side effects, including chest pain. There was no change in blood pressure or respiratory rate during concurrent adenosine and theophylline.(9) In a study in ten dog and twelve human subjects, the administration of adenosine after hexobendine increased coronary sinus blood flow. Aminophylline administration significantly decreased the coronary vasodilation response to adenosine and hexobendine.(5) In a study in ten healthy subjects, caffeine reduced the mean adenosine-induced increases in systolic blood pressure by 7.2 mmHg and heart rate by 8.4 beats/min when compared to placebo.(2) In another study in ten healthy subjects, caffeine was shown to lower the adenosine-induced response of blood pressure and heart rate.(3) Caffeine has also been reported to reduced adenosine-induced changes in minute ventilation and tidal volume.(3) Aminophylline has been shown to shorten the duration of coronary blood flow response to regadenoson.(3) Coronary flow reserve was 8% lower in patients who received caffeine (200 mg single dose) 2 hours prior to regadenoson administration when compared to subjects who received placebo instead of caffeine.(4)

Xanthine Derivatives/Dipyridamole Injectable

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: The xanthine derivatives are adenosine receptor antagonists. Concurrent administration may inhibit dipyridamole-induced increases in endogenous plasma adenosine levels, thus decreasing dipyridamole's vasodilator effects.(1)

CLINICAL EFFECTS: Concurrent administration may result in a decrease in dipyridamole's vasodilator effects. This may produce false-negative results during dipyridamole-thallium imaging tests.(1-3)

PREDISPOSING FACTORS: In patients with congestive heart failure and decreased hepatic function, the metabolism of xanthine derivatives may be decreased. These patients may need a longer xanthine-free period prior to dipyridamole-thallium imaging tests.(2)

PATIENT MANAGEMENT: Patients scheduled for dipyridamole-thallium imaging tests should have a xanthine-free period (including caffeine-containing products) for at least 24 hours prior to their exam.(3)

DISCUSSION: In a study in eight male subjects with documented coronary artery disease, intravenous dipyridamole administered during a dipyridamole-thallium 201 SPECT image test produced a significant increase in heart rate, a decrease in blood pressure, and angina in seven patients and ST segment depression in four patients. SPECT imaging showed reversible perfusion defects in myocardial segments supplied by stenotic coronary arteries. When the exam was repeated when the subjects were receiving therapeutic dosages of theophylline, there was no appearance of angina, ST depression, or hemodynamic changes and SPECT imaging shown total absence of reversible perfusion defects.(1) A study in eight patients with coronary artery disease evaluated the effects of caffeine on dipyridamole-201Tl myocardial imaging. The administration of dipyridamole alone resulted in chest pain and ST-segment depression in four patients. Concurrent caffeine infusion decreased the dipyridamole-induced decrease in blood pressure and heart rate. No patients experience chest pain or ST-segment depression. Six patients had false negative test results.(2) Another study found that the attenuation of the hemodynamic response to dipyridamole by caffeine was dose-dependent.(3)

Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

Cyp3a4 Inducers/Erlotinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Inducers of CYP3A4 may induce the metabolism of erlotinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a CYP3A4 inducer may result in decreased levels and effectiveness of erlotinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of CYP3A4 inducers in patients receiving therapy with erlotinib. Consider the use of alternative agents with less enzyme induction potential.(1) Consider increasing the dosage of erlotinib by 50 mg increments as tolerated at two week intervals (to a maximum of 450 mg) while closely monitoring the patient. The highest dosage studied with concurrent rifampin is 450 mg. If the dosage of erlotinib is increased, it will need to be decreased when the inducer is discontinued.(1)

DISCUSSION: Pretreatment and concurrent therapy with rifampin increased erlotinib clearance by 3-fold and decreased the erlotinib area-under-curve (AUC) by 66% to 80%. This is equivalent to a dose of about 30 mg to 50 mg in NSCLC.(1) In a study, pretreatment with rifampin for 11 days decreased the AUC of a single 450 mg dose of erlotinib to 57.6% of the AUC observed with a single 150 mg dose of erlotinib.(1) In a case report, coadministration of phenytoin (180mg daily) and erlotinib (150mg daily) increased the phenytoin concentration from 8.2mcg/ml to 24.2mcg/ml and decreased the erlotinib concentration 12-fold (from 1.77mcg/ml to 0.15mcg/ml) and increased the erlotinib clearance by 10-fold (from 3.53 L/h to 41.7 L/h).(2) In a study, concurrent use of sorafenib (400 mg twice daily) and erlotinib (150 mg daily) decreased the concentration minimum (Cmin), concentration maximum (Cmax), and AUC of erlotinib.(3) In an animal study, concurrent use of dexamethasone and erlotinib decreased the AUC of erlotinib by 0.6-fold.(4) Strong inducers of CYP3A4 include: barbiturates, encorafenib, enzalutamide, fosphenytoin, ivosidenib, mitotane, phenobarbital, phenytoin, primidone, rifampin, and rifapentine.(5,6) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, sotorasib, telotristat, thioridazine, and tovorafenib.(5,6) Weak inducers of CYP3A4 include: amprenavir, armodafinil, aumolertinib, bexarotene, brigatinib, brivaracetam, clobazam, danshen, darolutamide, dicloxacillin, echinacea, eslicarbazepine, flucloxacillin, garlic, genistein, ginkgo, ginseng, glycyrrhizin, mobocertinib, nevirapine, omaveloxolone, oritavancin, oxcarbazepine, pioglitazone, pitolisant, quercetin, relugolix, rufinamide, sarilumab, sulfinpyrazone, sunvozertinib, tazemetostat, tecovirimat, terbinafine, ticlopidine, topiramate, troglitazone, vemurafenib, vinblastine, and zanubrutinib.(5,6)

Selected Moderate And Weak Cyp1a2 Inhibitors/Tizanidine

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate and weak CYP1A2 inhibitors may inhibit the metabolism of tizanidine by CYP1A2.(1)

CLINICAL EFFECTS: Concurrent use of moderate and weak CYP1A2 inhibitors may result in elevated levels of and effects from tizanidine, including hypotension, bradycardia, drowsiness, sedation, and decreased psychomotor function.

PREDISPOSING FACTORS: The risk of anticholinergic toxicities including cognitive decline, delirium, falls and fractures is increased in geriatric patients using more than one medicine with anticholinergic properties.(2)

PATIENT MANAGEMENT: The US manufacturer of tizanidine states that concurrent use of tizanidine with inhibitors of CYP1A2 should be avoided.(3) If adverse reactions such as hypotension, bradycardia or excessive drowsiness occur, reduce tizanidine dosage or discontinue tizanidine therapy.(3)

DISCUSSION: In a study, cannabidiol 750 mg twice daily (a weak CYP1A2 inhibitor) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a 200 mg single dose of caffeine (a sensitive CYP1A2 substrate) by 15% and 95%, respectively.(1) In a study in 10 healthy subjects, concurrent fluvoxamine, a strong inhibitor of CYP1A2, increased tizanidine Cmax, AUC, and half-life (T1/2) by 12-fold, 33-fold, and 3-fold, respectively. Significant decreases in blood pressure and increases in drowsiness and psychomotor impairment occurred.(3) In a study in 10 healthy subjects, concurrent ciprofloxacin, a strong inhibitor of CYP1A2, increased tizanidine Cmax and AUC by 7-fold and 10-fold, respectively. Significant decreases in blood pressure and increases in drowsiness and psychomotor impairment occurred.(3) Moderate CYP1A2 inhibitors linked to this monograph include: centanafadine, dipyrone, fexinidazole, genistein, methoxsalen, phenylpropanolamine, pipemidic acid, propranolol, rucaparib, and troleandomycin. Weak CYP1A2 inhibitors linked to this monograph include: allopurinol, artemisinin, belumosudil, caffeine, cannabidiol, curcumin, dan-shen, disulfiram, Echinacea, ginseng, parsley, piperine, ribociclib, simeprevir, thiabendazole, and triclabendazole.(4)

Moderate Interaction: Assess the risk to the patient and take action as needed.

Caffeine-Containing Products/Migalastat

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: The mechanism of this interaction is unknown.

CLINICAL EFFECTS: Concurrent use of a caffeine-containing product may result in decreased levels and effectiveness of migalastat.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid coadministration of migalastat with caffeine-containing products. Do not administer caffeine-containing products within 2 hours before and 2 hours after taking migalastat.(1)

DISCUSSION: Coadministration of migalastat with caffeine 190 mg decreased the migalastat maximum concentration (Cmax) by 60% and area-under-curve (AUC) by 55%.(1)

Green Tea/Nadolol

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Nadolol is a substrate of OATP1A2, an influx transporter found in intestinal epithelium. Green tea catechins inhibit several drug transporters, including OATP1A2, leading to decreased absorption of nadolol. P-glycoprotein may also be involved, however no studies have confirmed its role.

CLINICAL EFFECTS: Concomitant use of nadolol with green tea or green tea catechins may decrease the effectiveness of nadolol.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Advise patients maintained on nadolol to avoid green tea and green tea supplements.

DISCUSSION: In a randomized crossover study in 10 healthy subjects, concurrent use of nadolol (30 mg daily) and green tea (700 mL/day), decreased the maximum concentration (Cmax) and area-under-curve (AUC) of nadolol by 85.3% and 85%, respectively. Pharmacodynamic parameters assessed included pulse rate, systolic blood pressure, and diastolic blood pressure. Although all parameters were affected slightly, nadolol's systolic blood pressure lowering effect was significantly suppressed (p = 0.042).(1)

Moderate And Weak Cyp3a4 Inducers/Tacrolimus

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Moderate or weak CYP3A4 inducers may accelerate the metabolism of tacrolimus.(1)

CLINICAL EFFECTS: Concurrent use of a moderate or weak CYP3A4 inducer may result in decreased levels and effectiveness of tacrolimus.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of tacrolimus recommends monitoring tacrolimus whole blood trough concentrations and adjusting tacrolimus dose if needed. Monitor clinical response closely.(1)

DISCUSSION: A 13-year-old cystic fibrosis patient with a history of liver transplant on stable doses of tacrolimus underwent 2 separate courses of nafcillin therapy (a moderate CYP3A4 inducer). During the 1st course of nafcillin, his tacrolimus levels started to fall 3 days after starting nafcillin, became undetectable at day 8, and recovered to therapeutic levels without a change in tacrolimus dose 5 days after discontinuation of nafcillin. During the 2nd course of nafcillin, tacrolimus level became undetectable 4 days after starting nafcillin and recovered 3 days after stopping nafcillin.(2) Moderate inducers of CYP3A4 would be expected to decrease the AUC of a sensitive 3A4 substrate by 50-80% and include: belzutifan, bosentan, cenobamate, dabrafenib, elagolix, etravirine, lesinurad, lorlatinib, mavacamten, modafinil, nafcillin, repotrectinib, telotristat, and tovorafenib.(3,4) Weak inducers of CYP3A4 would be expected to decrease the AUC of a sensitive 3A4 substrate by 20-50% and include: armodafinil, bexarotene, brigatinib, brivaracetam, clobazam, danshen, darolutamide, dexamethasone, dicloxacillin, echinacea, elafibranor, enasidenib, eslicarbazepine, floxacillin, garlic, genistein, ginseng, glycyrrhizin, meropenem-vaborbactam, nevirapine, oritavancin, omaveloxolone, oxcarbazepine, pioglitazone, relugolix, rufinamide, sulfinpyrazone, sunvozertinib, suzetrigine, tazemetostat, tecovirimat, terbinafine, ticlopidine, topiramate, troglitazone, vinblastine, and zanubrutinib.(3,4)

Moderate And Weak Cyp3a4 Inducers/Ubrogepant

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Moderate or weak CYP3A4 inducers may induce the metabolism of ubrogepant.(1)

CLINICAL EFFECTS: Concurrent use of a moderate or weak CYP3A4 inducer may result in decreased levels and effectiveness of ubrogepant.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer recommends a dosage adjustment of ubrogepant when coadministered with moderate or weak CYP3A4 inducers. Initial dose of ubrogepant should be 100 mg. If a second dose is needed, the dose of ubrogepant should be 100 mg.(1)

DISCUSSION: Coadministration of ubrogepant with rifampin, a strong CYP3A4 inducer, resulted in an 80% reduction in ubrogepant exposure. No dedicated drug interaction studies were conducted to assess concomitant use with moderate or weak CYP3A4 inducers. Dose adjustment for concomitant use of ubrogepant with moderate or weak CYP3A4 inducers is recommended based on a conservative prediction of 50% reduction in exposure of ubrogepant.(1) Moderate inducers of CYP3A4 would be expected to decrease the AUC of a sensitive 3A4 substrate by 50-80% and include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pexidartinib, rifabutin, telotristat, thioridazine, and tovorafenib.(2,3) Weak inducers of CYP3A4 would be expected to decrease the AUC of a sensitive 3A4 substrate by 20-50% and include: armodafinil, bexarotene, brigatinib, brivaracetam, clobazam, danshen, dexamethasone, dicloxacillin, echinacea, elafibranor, eslicarbazepine, floxacillin, garlic, genistein, ginseng, glycyrrhizin, meropenem-vaborbactam, methylprednisolone, nevirapine, omaveloxolone, oritavancin, oxcarbazepine, pioglitazone, pitolisant, relugolix, repotrectinib, rufinamide, sarilumab, sulfinpyrazone, sunvozertinib, suzetrigine, tazemetostat, tecovirimat, terbinafine, ticlopidine, topiramate, troglitazone, vemurafenib, vinblastine, and zanubrutinib.(2,3)

Selected Cyp1a2 Inhibitors/Theophylline Derivatives

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: CYP1A2 inhibitors may reduce the elimination rate of theophylline derivatives.

CLINICAL EFFECTS: The concurrent administration of selected CYP1A2 inhibitors and theophylline or their derivatives may result in increased levels and toxicity of theophylline.(1-19)

PREDISPOSING FACTORS: Concomitant therapy with inhibitors of CYP3A4 (e.g. clarithromycin, itraconazole, ritonavir) which block a secondary metabolic pathway for theophylline, may increase the magnitude of this interaction.

PATIENT MANAGEMENT: Theophylline levels should be closely monitored in patients receiving concurrent therapy. The dosage of theophylline may need to be decreased after a CYP1A2 inhibitor is initiated. If the CYP1A2 inhibitor is discontinued in a patient stabilized on the combination, the theophylline level may fall. Monitor theophylline levels and adjust dose accordingly.

DISCUSSION: A study in 5 patients with active hepatitis B and 4 healthy subjects examined the effects of a single dose of interferon alpha (9 million units in 8 subjects, 18 million units in 1 subject). There was no effect on theophylline in 1 subject. In the other 8 subjects, interferon increased theophylline half-life by 70% and decreased theophylline clearance by 49% (range 33% to 81%).(1) A study in 11 healthy subjects examined the effects of interferon alpha (3 million International Units daily for 3 days) on a single aminophylline (4 mg/kg) infusion. Interferon increased the half-life, area-under-curve (AUC), and mean residence time by 13.7%, 17.9%, and 16.3%, respectively. Theophylline clearance decreased by 9.1%.(2) In a study in healthy males, peginterferon alfa-2a (180 mcg once weekly for 4 weeks) increased theophylline AUC by 25%.(3,4) Concurrent interferon alfa has been shown to increase theophylline levels by 100%.(5) A study in 7 patients with chronic hepatitis C examined the effects of interferon beta (3 million to 9 million International Units daily for 8 weeks) on theophylline ethylenediamine (single 250 mg infusion). Interferon decreased theophylline clearance by 26.3% and increased theophylline half-life by 39.3%. There was no correlation between interferon dose and effect. The greatest effect was seen in a patient who received 3 million International Units daily, while no effect was seen in a patient who received 9 million International Units daily.(6) Increased serum theophylline levels with signs and symptoms of theophylline toxicity have been reported in patients following the addition of mexiletine to their treatment.(7-15) In a study evaluated the combination of disulfiram and theophylline in 20 recovering alcoholics. Patients received a single IV dose of theophylline while being given either 250 mg or 500 mg of disulfiram daily. Both dosages of disulfiram decreased the clearance of theophylline. However, the effect was greatest in patients receiving disulfiram 500 mg daily.(16) Increases in serum theophylline concentration and half-life have been reported during concurrent administration of theophylline and ticlopidine.(17) In healthy subjects, rofecoxib (12.5 mg/day, 25 mg/day, or 50 mg/day for seven days) increased the area-under-curve (AUC) of a single dose of theophylline (300 mg) by 38% to 60%. Therefore, the manufacturer of rofecoxib recommends that theophylline levels be monitored if rofecoxib is initiated or changed in patients receiving theophylline.(18) Selected CYP1A2 inhibitors linked to this monograph include: acyclovir, Angelica dahurica, artemisinin, belumosudil, centanafadine, cannabidiol, curcumin, danshen, dipyrone, disulfiram, echinacea, enasidenib, fexinidazole, genistein, ginseng, interferons, methoxsalen, mexiletine, parsley, phenylpropanolamine, pipemidic acid, piperine, propafenone, ribociclib, rofecoxib, rucaparib, simeprevir, ticlopidine, triclabendazole, valacyclovir, and verapamil.(19)

Selected Moderate-Weak Cyp3a4 Inducers/Exemestane

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: CYP3A4 inducers may induce the metabolism of exemestane.(1)

CLINICAL EFFECTS: Concurrent use of a CYP3A4 inducer may result in decreased levels and effectiveness of exemestane.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of exemestane recommends that patients receiving concurrent therapy with a strong CYP3A4 inducer receive 50 mg of exemestane daily after a meal.(1) It may be prudent to consider a dosage increase for patients receiving weaker CYP3A4 inducers.

DISCUSSION: In a study in 10 healthy postmenopausal subjects, pretreatment with rifampin (a strong CYP3A4 inducer, 600 mg daily for 14 days) decreased the area-under-curve (AUC) and maximum concentration (Cmax) of a single dose of exemestane (25 mg) by 54% and 41%, respectively.(1) Strong inducers of CYP3A4 would be expected to decrease the AUC of a sensitive 3A4 substrate by 80% or more and include: carbamazepine, enzalutamide, mitotane, phenobarbital, phenytoin, rifabutin, rifampin, and St. John's wort.(1-3) Moderate inducers of CYP3A4 would be expected to decrease the AUC of a sensitive 3A4 substrate by 50-80% and include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3) Weak inducers of CYP3A4 would be expected to decrease the AUC of a sensitive 3A4 substrate by 20-50% and include: armodafinil, aumolertinib, bexarotene, brigatinib, brivaracetam, clobazam, danshen, darolutamide, dexamethasone, dicloxacillin, echinacea, elafibranor, enasidenib, eslicarbazepine, floxacillin, garlic, gingko, ginseng, glycyrrhizin, lorlatinib, meropenem-vaborbactam, methylprednisolone, nevirapine, omaveloxolone, oritavancin, oxcarbazepine, pioglitazone, pitolisant, quercetin, relugolix, rufinamide, sarilumab, sulfinpyrazone, sunvozertinib, suzetrigine, tazemetostat, tecovirimat, terbinafine, ticlopidine, topiramate, troglitazone, vemurafenib, vinblastine, and zanubrutinib.(2,3)

Selected Weak Cyp2d6 Inhibitors/Tamoxifen

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Inhibitors of CYP2D6 may inhibit the conversion of tamoxifen to endoxifen (an active metabolite of tamoxifen).(1-2) The role of endoxifen in tamoxifen's efficacy has been debated and may involve a minimum concentration level.(3-5)

CLINICAL EFFECTS: Concurrent use of inhibitors of CYP2D6 may decrease the effectiveness of tamoxifen in preventing breast cancer recurrence.

PREDISPOSING FACTORS: Concurrent use of weak CYP2D6 inhibitors in patients who are CYP2D6 intermediate metabolizers should be avoided. Patients who are CYP2D6 poor metabolizers lack CYP2D6 function and are not affected by CYP2D6 inhibition.

PATIENT MANAGEMENT: Although data on this interaction are conflicting, it may be prudent to use alternatives to CYP2D6 inhibitors when possible in patients taking tamoxifen. The US manufacturer of tamoxifen states that the impact on the efficacy of tamoxifen by strong CYP2D6 inhibitors is uncertain and makes no recommendation regarding coadministration with inhibitors of CYP2D6.(12) The manufacturer of paroxetine (a strong CYP2D6 inhibitor) states that alternative agents with little or no CYP2D6 inhibition should be considered.(13) The National Comprehensive Cancer Network's breast cancer guidelines advises caution when coadministering strong CYP2D6 inhibitors with tamoxifen.(14) NCCN states when prescribing a selective serotonin reuptake inhibitor (SSRI), it is reasonable to avoid SSRIs that are strong and moderate CYP2D6 inhibitors, particularly fluoxetine and paroxetine, if an appropriate alternative exists.(14) Cancer Care Ontario breast cancer guidelines state concurrent use of weak CYP2D6 inhibitors should be closely monitored.(15) The European Society of Medical Oncology (ESMO) clinical practice guidelines for early breast cancer states patients on tamoxifen should be advised to avoid concurrent use of strong and moderate CYP2D6 inhibitors. Consider alternatives to tamoxifen if CYP2D6 inhibitors cannot be replaced with alternative agents.(16) If concurrent therapy is warranted, the risks versus benefits should be discussed with the patient.

DISCUSSION: Some studies have suggested that administration of fluoxetine, paroxetine, and quinidine with tamoxifen or a CYP2D6 poor metabolizer phenotype may result in a decrease in the formation of endoxifen (an active metabolite of tamoxifen) and a shorter time to breast cancer recurrence.(1-2,9) A retrospective study of 630 breast cancer patients found an increasing risk of breast cancer mortality with increasing durations of coadministration of tamoxifen and paroxetine. In the adjusted analysis, absolute increases of 25%, 50%, and 75% in the proportion of time of overlapping use of tamoxifen with paroxetine was associated with 24%, 54%, and 91% increase in the risk of death from breast cancer, respectively.(18) The CYP2D6 genotype of the patient may have a role in the effects of this interaction. Patients with wild-type CYP2D6 genotype may be affected to a greater extent by this interaction. Patients with a variant CYP2D6 genotype may have lower baseline levels of endoxifen and may be affected to a lesser extent by this interaction.(6-10) In a retrospective review, 1,325 patients treated with tamoxifen for breast cancer were classified as being poor 2D6 metabolizers (lacking functional CYP2D6 enzymes), intermediate metabolizers (heterozygous alleles), or extensive metabolizers (possessing 2 functional alleles). After a mean follow-up period of 6.3 years, the recurrence rates were 14.9%, 20.9%, and 29.0%, in extensive metabolizers, intermediate metabolizers, and poor metabolizers, respectively.(11) In October of 2006, the Advisory Committee Pharmaceutical Science, Clinical Pharmacology Subcommittee of the US Food and Drug Administration recommended that the US tamoxifen labeling be updated to include information about the increased risk of breast cancer recurrence in poor CYP2D6 metabolizers (either by genotype or drug interaction).(19-20) The labeling changes were never made due to ongoing uncertainty about the effects of CYP2D6 genotypes on tamoxifen efficacy. In contrast to the above information, two studies have shown no relationship between CYP2D6 genotype and breast cancer outcome.(21-23) As well, a number of studies found no association between use of CYP2D6 inhibitors and/or antidepressants in patients on tamoxifen and breast cancer recurrence,(24-28) though the studies were limited by problematic selection of CYP2D6 inhibitors and short follow-up. Weak inhibitors of CYP2D6 include: alogliptin, artesunate, celecoxib, chloroquine, cimetidine, clobazam, clomipramine, cobicistat, delavirdine, diltiazem, dimenhydrinate, diphenhydramine, dronabinol, dupilumab, echinacea, enasidenib, fedratinib, felodipine, fluvoxamine, gefitinib, hydralazine, imatinib, labetalol, lorcaserin, nicardipine, osilodrostat, ranitidine, ritonavir, sarpogrelate, sertraline, verapamil and viloxazine.(29)

Theophylline Derivatives/Lithium

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Theophylline derivatives increase the renal excretion of lithium.

CLINICAL EFFECTS: Decreased levels of lithium which may result in decreased clinical effectiveness.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Lithium levels and response should be monitored in patients in whom theophylline therapy is initiated or withdrawn. Patients receiving concurrent therapy should be monitored for increased adverse effects.

DISCUSSION: In a study involving ten volunteers, the concurrent administration of lithium and theophylline resulted in a significant decrease in lithium serum levels. Upon discontinuation of theophylline, lithium levels and half-life increased, and the clearance of lithium decreased. Individual variability in these parameters was significant. The overall incidence of adverse effects was significantly greater with concurrent therapy including restlessness, tremor, and anorexia. In another study in ten normal subjects, lithium (1200 mg/day for seven days) was administered and it was reported that theophylline infusion (dosed to achieve a plasma level of 14 mcg/ml) increased lithium clearances by 51%. In a case report, reduced lithium levels as well as worsening of manic symptoms occurred after increasing doses of theophylline were administered. It has been shown that aminophylline increases the lithium/creatinine clearance ratio, which may result in decreased serum lithium below the therapeutic level. Caffeine withdrawal has been reported to increase lithium levels in several case reports. This interaction is most important to consider in patients who have been previously sensitive to relapse with decreased lithium levels and in whom levels are maintained at the therapeutic/prophylactic borderline.

Weak Cyp2d6 Inhibitors/Eliglustat

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Weak inhibitors of CYP2D6 may inhibit the metabolism of eliglustat. If the patient is also taking an inhibitor of CYP3A4, eliglustat metabolism can be further inhibited.(1)

CLINICAL EFFECTS: Concurrent use of an agent that is a weak inhibitor of CYP2D6 may result in elevated levels of and clinical effects of eliglustat, including prolongation of the PR, QTc, and/or QRS intervals, which may result in life-threatening cardiac arrhythmias.(1)

PREDISPOSING FACTORS: If the patient is also taking an inhibitor of CYP3A4 and/or has hepatic impairment, eliglustat metabolism can be further inhibited.(1) The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The dosage of eliglustat with weak inhibitors of CYP2D6 in poor CYP2D6 metabolizers should be limited to 84 mg daily.(1) The dosage of eliglustat with weak inhibitors of CYP2D6 in extensive CYP2D6 metabolizers with mild (Child-Pugh Class A) hepatic impairment should be limited to 84 mg daily.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Paroxetine (30 mg daily), a strong inhibitor of CYP2D6, increased eliglustat (84 mg BID) maximum concentration (Cmax) and area-under-curve (AUC) by 7-fold and 8.4-fold, respectively, in extensive metabolizers. Physiologically-based pharmacokinetic (PKPB) models suggested paroxetine would increase eliglustat Cmax and AUC by 2.1-fold and 2.3-fold, respectively, in intermediate metabolizers. PKPB models suggested ketoconazole may increase the Cmax and AUC of eliglustat (84 mg daily) by 4.3-fold and 6.2-fold, respectively, in poor metabolizers.(1) PKPB models suggested terbinafine, a moderate inhibitor of CYP2D6, would increase eliglustat Cmax and AUC by 3.8-fold and 4.5-fold, respectively, in extensive metabolizers and by 1.6-fold and 1.6-fold, respectively in intermediate metabolizers. PKPB models suggest that concurrent eliglustat (84 mg BID), paroxetine (a strong inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 16.7-fold and 24.2-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 7.5-fold and 9.8-fold, respectively.(1) PKPB models suggest that concurrent eliglustat (84 mg BID), terbinafine (a moderate inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 10.2-fold and 13.6-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 4.2-fold and 5-fold, respectively.(1) A single dose of rolapitant increased dextromethorphan, a CYP2D6 substrate, about 3-fold on days 8 and day 22 following administration. Dextromethorphan levels remained elevated by 2.3-fold on day 28 after single dose rolapitant. The inhibitory effects of rolapitant on CYP2D6 are expected to persist beyond 28 days.(5) Weak inhibitors of CYP2D6 include: alogliptin, artesunate, celecoxib, chloroquine, chlorpromazine, clobazam, clomipramine, desvenlafaxine, dimenhydrinate, diphenhydramine, dronabinol, dupilumab, echinacea, enasidenib, felodipine, gefitinib, hydralazine, hydroxychloroquine, lorcaserin, methadone, panobinostat, propafenone, sarpogrelate, sertraline, vemurafenib, and venlafaxine.(3,4)

Weak Cyp3a4 Inducers/Atogepant

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Weak CYP3A4 inducers may increase the metabolism of atogepant by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of weak CYP3A4 inducers with atogepant may result in decreased levels and clinical effectiveness of atogepant.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of atogepant recommends that patients on concomitant weak CYP3A4 inducers receive atogepant 30 mg or 60 mg once daily for prevention of episodic migraines and receive atogepant 60 mg once daily for prevention of chronic migraines.(1) Patients receiving concurrent therapy with CYP3A4 inducers and atogepant should be observed for decreased clinical effectiveness.

DISCUSSION: In a study of healthy subjects, rifampin, a strong CYP3A4 inducer, decreased the area-under-curve (AUC) and maximum concentration (Cmax) of atogepant by 60% and 30%, respectively. Topiramate, a weak CYP3A4 inducer, decreased atogepant AUC and Cmax by 25% and 24%, respectively.(1) Weak CYP3A4 inducers linked to this monograph include: armodafinil, aumolertinib, bexarotene, brigatinib, brivaracetam, clobazam, danshen, darolutamide, dexamethasone, dicloxacillin, echinacea, eslicarbazepine, floxacillin, garlic, genistein, ginseng, glycyrrhizin, methylprednisolone, mobocertinib, nevirapine, omaveloxolone, oritavancin, oxcarbazepine, pioglitazone, pitolisant, quercetin, relugolix, rufinamide, sarilumab, sulfinpyrazone, tazemetostat, tecovirimat, terbinafine, ticlopidine, topiramate, troglitazone, vemurafenib, vinblastine, and zanubrutinib.(1,2)

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